1. Field of the Invention
The present invention relates to a light emitting diode (LED) package and a light emitting apparatus having the same, and more particularly, to a chip-type LED package and a light emitting apparatus having the same.
2. Discussion of the Background
Generally, a chip-type LED package includes an LED chip mounted on a printed circuit board (PCB) and a molding portion covering the LED chip. The molding portion contains a phosphor to convert the wavelength of light emitted from the LED chip. For example, the LED chip may be a gallium nitride-based compound semiconductor capable of emitting ultraviolet or blue light, and the phosphor converts the ultraviolet or blue light into light with another color. Accordingly, it is possible to implement light with various colors, particularly white light, by combining the LED chip with the phosphor.
Since this chip-type LED package has a very simple structure, a manufacturing process is simplified and it is possible to mass-produce light, thin, simple and small products. Accordingly, the chip-type LED package is widely used for various application products that require small light sources, for example, as a backlight source for a liquid crystal display (LCD) of a mobile communication terminal.
Conventionally, the molding portion containing the phosphor is formed by dotting or casting a liquid epoxy resin containing the phosphor onto a PCB. However, since an inorganic phosphor has relatively greater specific gravity than the liquid epoxy resin, the phosphor precipitates within the liquid epoxy resin. Accordingly, since the phosphor is irregularly dispersed within the molding portion, it is not possible to provide an LED package with uniform luminance.
Meanwhile, Korean Patent No. 10-0348377 discloses a method of manufacturing a chip-type LED package having a molding portion with a phosphor uniformly dispersed therein. FIG. 1 is a sectional view illustrating the method of manufacturing a chip-type LED package disclosed in the Korean patent.
Referring to FIG. 1, an LED chip 3 is mounted on a PCB 6 with lead electrodes 7 printed thereon. The LED chip 3 is mounted on and electrically connected to any one of the lead electrodes 7 using a conductive adhesive 4 and is also electrically connected to the other of the lead electrodes 7 by means of a bonding wire 5.
Meanwhile, a molding portion 1 containing a phosphor 2 covers the LED chip 3. The molding portion 1 is formed by making a tablet out of a mixture of the phosphor 2 and solid resin powder and then performing transfer molding using the tablet. During transfer molding, the molding portion is formed by curing a resin within a short period of time at a temperature relatively higher than a general curing temperature. It is possible to prevent precipitation of the phosphor 2 within the molding portion 1 due to a difference in specific gravity, resulting in the molding portion 1 with the phosphor 2 uniformly dispersed therein. Accordingly, it is possible to provide a chip-type LED package having uniform luminance due to the molding portion 1 with the phosphor 2 uniformly dispersed therein.
The molding portion 1 has a high hardness in order to protect the LED chip against external forces and other environmental hazards. However, where the molding portion 1 covering the LED chip has a high hardness, the molding portion 1 may be deformed due to thermal stress generated during operation of the LED chip. The deformation of the molding portion 1 causes variations in light emitting luminance and also causes separation of the molding portion 1 from the PCB 6, thereby shortening the life span of the LED package.
In order to meet development of color realization and demand for enhancing LCD brightness, a chip-type LED package with high output power may be used as a backlight source. To this end, a chip-type LED package on which a power chip operating at a relatively significantly higher current such as about 350 mA, compared with a conventional LED chip operating at about 20 mA, is mounted. However, an increase of the operating current increases heat generation from the LED chip, and thus, the molding portion is more deformed. In addition, since a PCB made of glass epoxy with low thermal conductivity cannot rapidly dissipate heat generated from the LED chip, the thermal deformation of the molding portion is further promoted.